A network processor generally controls the flow of packets between a physical transmission medium, such as a physical layer portion of, e.g., an asynchronous transfer mode (ATM) network or synchronous optical network (SONET), and a switch fabric in a router or other type of packet switch. Such routers and switches generally include multiple network processors, e.g., arranged in the form of an array of line or port cards with one or more of the processors associated with each of the cards.
A conventional network processor may include, among other elements, an internal memory and an associated internal memory controller. Such a network processor also includes a number of clients, where the term “client” as used in conjunction with a given network processor or other processor generally denotes a particular logic block, or other processing element of the processor, that requires access to the internal memory. Particular portions of the internal memory are commonly referred to as “memory instances.” The internal memory controller controls access of the processor clients to the memory instances of the internal memory. One or more of the clients may access external memory instances, in place of or in addition to the internal memory instances accessed by those clients.
A problem that can arise in conventional network processors is that such processors are typically implemented such that the internal memory controller does not permit different clients to access different ones of the memory instances in a configurable manner. More specifically, the network processor generally cannot be configured such that any client can be connected to any of the memory instances. Instead, such conventional network processors may simply allow multiple clients to share a given memory instance, or may simply connect a client to a dedicated memory instance. This fails to provide an adequate degree of configuration flexibility, and thus unduly limits the internal memory bandwidth and throughput performance that are achievable in the network processor. It may also increase the amount of internal memory that is required in order to provide support for given set of client applications, which in turn increases the size, cost and power consumption of the processor.
Accordingly, a need exists for an improved memory controller, for use in a network processor or other type of processor, which provides improved configuration flexibility in connecting processor clients to internal memory instances.